03 cavalier won't start

My 2003 cavalier with 65000 miles just started having problems starting when hot and now sometimes even cold. It will crank but not start. If I hold the the gas pedal to the floor it will finally start. After a few minutes of holding it above an idle until the idle smooths, then it runs fine. I changed the coolant temp. sensor but it's still doing it. Is it possibly the air charge sensor?
Any suggestions?

Thanks,

have you ever changed your fuel filter?

Thanks Mangoamerican. I haven't changed the fuel filter but I think I found my problem. About a month ago I degreased and washed my engine. I think by doing so it created just enough corrosian on the negative cable at the connection at the bottom of the battery tray to allow the engine to crank but not enough voltage was being sent to the injectors. I got lucky and happened to see a little bit of green corrosian coming from the edge of the cable. I cleaned the connection and everything runs fine now.

Thanks.